1. Field of the Invention
The present invention relates to a resistor utilized in a servo amplifier used in a controller of an industrial equipment such as a machine tool, robot, an injection molding apparatus, a wire electric discharge device and an electric motor presses. The present invention is further related to a servo amplifier provided with this resistor.
2. Description of the Related Art
Servo amplifiers are provided with resistors which generate large amounts of heat such as regenerative resistors which function to consume regenerative current. When installing a resistor which generates large amount of heat in a servo amplifier, the resistor is mounted at location separated from the internal components of the amplifier as well as at the rear of the amplifier in order to eliminate the effects of heat on the internal components of the amplifier.
FIG. 3 shows an example of a conventional servo amplifier provided with a resistor that generates a large amount of heat. A semiconductor module, such as an inverter, and various circuit components 101 are arranged on the surface of a casing 104 of the servo amplifier. Heat sink 102 is disposed on the rear surface of the casing 104. This heat sink functions to release heat generated from the semiconductor module. Further, resistor 103 that generates large amounts of heat is mounted on the rear surface of the casing 104 separated from the heat sink 102 as well as from the various circuit components 101.
If a resistor is separated and mounted away from the internal components of the amplifier and if a resistor is separated and installed away from the internal components of the amplifier on the rear surface of the amplifier, the external shape of the amplifier will grow larger making it impossible to respond to demands for smaller sized servo amplifiers. Moreover, if heat generation passes through the casing of the amplifier and transfers to the inside of the amplifier, the temperature of the components inside the amplifier will rise and as a result lead to lower component lifecycles.